Precession occurs after how many degrees?

Precession occurs after how many degrees?

• A. 45 Degrees
• B. 120 Degrees
• C. 90 Degrees
• D. 180 Degrees

Answer: (C)

Precession is the sideways motion of a spinning rotor’s axis caused by a torque. The key is that the change in angular momentum (produced by the torque) occurs in a direction perpendicular to the spin axis. As the axis starts to tilt, this perpendicular response makes the axis sweep around the support in a circular path. That rotational motion of the axis effectively progresses through a quarter of a turn before the plane of tilt shows up in the original direction, which corresponds to a 90-degree change. In other words, the gyroscopic response is a 90-degree shift of the orientation of the spin axis relative to the initial plane, so the commonly cited amount for precession is 90 degrees.

Precession is the sideways motion of a spinning rotor’s axis caused by a torque. The key is that the change in angular momentum (produced by the torque) occurs in a direction perpendicular to the spin axis. As the axis starts to tilt, this perpendicular response makes the axis sweep around the support in a circular path. That rotational motion of the axis effectively progresses through a quarter of a turn before the plane of tilt shows up in the original direction, which corresponds to a 90-degree change. In other words, the gyroscopic response is a 90-degree shift of the orientation of the spin axis relative to the initial plane, so the commonly cited amount for precession is 90 degrees.